lity3d/Engine/Rendering/camera.c

#include "camera.h"

#include <math.h>
#include <string.h>

#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif

Camera camera_perspective(float fov_y, float aspect, float near_z, float far_z) {
    Camera cam = {0};
    cam.type = CAMERA_PERSPECTIVE;
    cam.position = (Vec3){0, 0, -5};
    cam.target = (Vec3){0, 0, 0};
    cam.up = (Vec3){0, 1, 0};
    cam.fov_y = fov_y;
    cam.aspect = aspect;
    cam.near_z = near_z;
    cam.far_z = far_z;
    cam.dirty = 1;
    return cam;
}

Camera camera_orthographic(float width, float height, float near_z, float far_z) {
    Camera cam = {0};
    cam.type = CAMERA_ORTHOGRAPHIC;
    cam.position = (Vec3){0, 0, -5};
    cam.target = (Vec3){0, 0, 0};
    cam.up = (Vec3){0, 1, 0};
    cam.ortho_width = width;
    cam.ortho_height = height;
    cam.near_z = near_z;
    cam.far_z = far_z;
    cam.dirty = 1;
    return cam;
}

void camera_update(Camera* camera) {
    if (!camera->dirty) return;
    mat4_lookat(&camera->position, &camera->target, &camera->up, &camera->view);

    if (camera->type == CAMERA_PERSPECTIVE) {
        mat4_perspective(camera->fov_y, camera->aspect, camera->near_z, camera->far_z, &camera->projection);
    } else {
        mat4_orthographic(camera->ortho_width, camera->ortho_height, camera->near_z, camera->far_z, &camera->projection);
    }
    camera->dirty = 0;
}

const Mat4* camera_get_view(Camera* camera) {
    camera_update(camera);
    return &camera->view;
}

const Mat4* camera_get_projection(Camera* camera) {
    camera_update(camera);
    return &camera->projection;
}

void camera_move_forward(Camera* camera, float distance) {
    Vec3 dir;
    vec3_sub(&camera->target, &camera->position, &dir);
    vec3_normalize(&dir, &dir);
    Vec3 move;
    vec3_scale(&dir, distance, &move);
    vec3_add(&camera->position, &move, &camera->position);
    vec3_add(&camera->target, &move, &camera->target);
    camera->dirty = 1;
}

void camera_move_right(Camera* camera, float distance) {
    Vec3 forward, right;
    vec3_sub(&camera->target, &camera->position, &forward);
    vec3_normalize(&forward, &forward);
    vec3_cross(&camera->up, &forward, &right);
    vec3_normalize(&right, &right);
    Vec3 move;
    vec3_scale(&right, distance, &move);
    vec3_add(&camera->position, &move, &camera->position);
    vec3_add(&camera->target, &move, &camera->target);
    camera->dirty = 1;
}

void camera_move_up(Camera* camera, float distance) {
    Vec3 move;
    vec3_scale(&camera->up, distance, &move);
    vec3_add(&camera->position, &move, &camera->position);
    vec3_add(&camera->target, &move, &camera->target);
    camera->dirty = 1;
}

void camera_rotate_yaw(Camera* camera, float angle) {
    Vec3 forward;
    vec3_sub(&camera->target, &camera->position, &forward);

    float cs = cosf(angle), sn = sinf(angle);
    Vec3 right;
    vec3_cross(&forward, &camera->up, &right);
    vec3_normalize(&right, &right);

    Vec3 new_forward = {
        forward.x * cs + right.x * sn,
        forward.y * cs + right.y * sn,
        forward.z * cs + right.z * sn,
    };
    vec3_add(&camera->position, &new_forward, &camera->target);
    camera->dirty = 1;
}

void camera_rotate_pitch(Camera* camera, float angle) {
    Vec3 forward;
    vec3_sub(&camera->target, &camera->position, &forward);

    Vec3 right;
    vec3_cross(&forward, &camera->up, &right);
    vec3_normalize(&right, &right);

    float cs = cosf(angle), sn = sinf(angle);
    Vec3 new_forward = {
        forward.x * cs + camera->up.x * sn,
        forward.y * cs + camera->up.y * sn,
        forward.z * cs + camera->up.z * sn,
    };

    Vec3 new_up;
    vec3_cross(&right, &new_forward, &new_up);
    camera->up = new_up;
    vec3_add(&camera->position, &new_forward, &camera->target);
    camera->dirty = 1;
}

void camera_look_at(Camera* camera, Vec3 target) {
    camera->target = target;
    camera->dirty = 1;
}